| First Author | Jansen S | Year | 2011 |
| Journal | J Biol Chem | Volume | 286 |
| Issue | 34 | Pages | 30087-96 |
| PubMed ID | 21685497 | Mgi Jnum | J:276418 |
| Mgi Id | MGI:6316567 | Doi | 10.1074/jbc.M111.251439 |
| Citation | Jansen S, et al. (2011) Mechanism of actin filament bundling by fascin. J Biol Chem 286(34):30087-96 |
| abstractText | Fascin is the main actin filament bundling protein in filopodia. Because of the important role filopodia play in cell migration, fascin is emerging as a major target for cancer drug discovery. However, an understanding of the mechanism of bundle formation by fascin is critically lacking. Fascin consists of four beta-trefoil domains. Here, we show that fascin contains two major actin-binding sites, coinciding with regions of high sequence conservation in beta-trefoil domains 1 and 3. The site in beta-trefoil-1 is located near the binding site of the fascin inhibitor macroketone and comprises residue Ser-39, whose phosphorylation by protein kinase C down-regulates actin bundling and formation of filopodia. The site in beta-trefoil-3 is related by pseudo-2-fold symmetry to that in beta-trefoil-1. The two sites are approximately 5 nm apart, resulting in a distance between actin filaments in the bundle of approximately 8.1 nm. Residue mutations in both sites disrupt bundle formation in vitro as assessed by co-sedimentation with actin and electron microscopy and severely impair formation of filopodia in cells as determined by rescue experiments in fascin-depleted cells. Mutations of other areas of the fascin surface also affect actin bundling and formation of filopodia albeit to a lesser extent, suggesting that, in addition to the two major actin-binding sites, fascin makes secondary contacts with other filaments in the bundle. In a high resolution crystal structure of fascin, molecules of glycerol and polyethylene glycol are bound in pockets located within the two major actin-binding sites. These molecules could guide the rational design of new anticancer fascin inhibitors. |
